Has anyone tried the Betsy-K in a sealed 1 or 1.5 cu. ft. cabinet? I haven't yet implemented my drivers. I have the "itch" but not the space at this time to set up such "large" enclosures. I would pair them experimentally with domes, ribbons, and planars.
Have you tried it, Paul?
Regards,
Karl
Have you tried it, Paul?
Regards,
Karl
Karl,
I honestly haven't gone that small sealed, but I have advised others to try it! I think it would work well in a moderately sized room placed close to the walls or corners. I'd think in terms of a wide baffle/shallow cabinet. Maybe even a Mapleshade style placement, very low and tilted back.
If you are planning a more traditional "bookshelf", (narrow baffle, stand, out in the room), then I'd use BSC. (Of course, there are plenty of folks out there who are happy with fullrange bookshelves and no BSC, but I like a little more bass). If you have a large room, you might want a sub with the sealed option. In smaller rooms, the room modes often extend the sealed cabs low enough to be pleasing. The nice thing is that if you do need a sub, only one is needed. Many other fullrangers in sealed boxes won't get low enough for a single sub.
I have used slightly larger sealed boxes, and I think the excursion reduction vs. a vented cab is well worth it (the lower distortion sounds nicer to my ear).
If you are looking for a small footprint, consider the skinny TL/TQWT I have yet to post plans for. 12"x13" footprint, 44" tall. I'm listening to a pair right now! They are a simple build, and you don't need to find stands. I spent some time thinking about these. Now if I could only get the dimensions exactly right in SketchUp. . .
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
I honestly haven't gone that small sealed, but I have advised others to try it! I think it would work well in a moderately sized room placed close to the walls or corners. I'd think in terms of a wide baffle/shallow cabinet. Maybe even a Mapleshade style placement, very low and tilted back.
If you are planning a more traditional "bookshelf", (narrow baffle, stand, out in the room), then I'd use BSC. (Of course, there are plenty of folks out there who are happy with fullrange bookshelves and no BSC, but I like a little more bass). If you have a large room, you might want a sub with the sealed option. In smaller rooms, the room modes often extend the sealed cabs low enough to be pleasing. The nice thing is that if you do need a sub, only one is needed. Many other fullrangers in sealed boxes won't get low enough for a single sub.
I have used slightly larger sealed boxes, and I think the excursion reduction vs. a vented cab is well worth it (the lower distortion sounds nicer to my ear).
If you are looking for a small footprint, consider the skinny TL/TQWT I have yet to post plans for. 12"x13" footprint, 44" tall. I'm listening to a pair right now! They are a simple build, and you don't need to find stands. I spent some time thinking about these. Now if I could only get the dimensions exactly right in SketchUp. . .
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
Karl,
Here is what Mapleshade says. The benefits are mainly that you get plenty of mid and low bass with no BSC. There are, of course, some downsides. Even with the speakers tilted back enough to be listening on axis with the fullrangers (or tweeters), the soundstage will be very low. You also have the potential for midrange reflections off the floor, but larger fullrangers won't be as much of a problem as smaller midranges (due to the directivity of the 8" fullranger). And if your bookshelf speaker has BSC, then you will end up with too much bass.
When I was using smaller sealed and vented boxes, I placed them on big concrete blocks. I had the blocks sitting on their smallest end, and the U shape provided adjustable tilt. I didn't care much about scratching those cabinets. I had them quite close to the wall.
Some folks like the sound with shelved down midbass/bass. The midrange really comes forward and puts vocalists in your lap. There are plenty of mini-monitors that use this trick. The lack of BSC also creates that distinctive forward midrange in the filter-less commercial fullrange vented bookshelves.
So, before you buy BSC parts, try it without. And then try the low placement. If you like the tonal balance of the low placement but find that you don't like the low soundstage or hear some reflection problem, then you can start to play with BSC.
Of course, another option is to use subs as your speaker stands ala the Bottlehead S.E.X.y speaker. You wouldn't need two with the BetsyK's, but those Parts Express pre-built subs are cheap enough that you may as well!
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
Here is what Mapleshade says. The benefits are mainly that you get plenty of mid and low bass with no BSC. There are, of course, some downsides. Even with the speakers tilted back enough to be listening on axis with the fullrangers (or tweeters), the soundstage will be very low. You also have the potential for midrange reflections off the floor, but larger fullrangers won't be as much of a problem as smaller midranges (due to the directivity of the 8" fullranger). And if your bookshelf speaker has BSC, then you will end up with too much bass.
When I was using smaller sealed and vented boxes, I placed them on big concrete blocks. I had the blocks sitting on their smallest end, and the U shape provided adjustable tilt. I didn't care much about scratching those cabinets. I had them quite close to the wall.
Some folks like the sound with shelved down midbass/bass. The midrange really comes forward and puts vocalists in your lap. There are plenty of mini-monitors that use this trick. The lack of BSC also creates that distinctive forward midrange in the filter-less commercial fullrange vented bookshelves.
So, before you buy BSC parts, try it without. And then try the low placement. If you like the tonal balance of the low placement but find that you don't like the low soundstage or hear some reflection problem, then you can start to play with BSC.
Of course, another option is to use subs as your speaker stands ala the Bottlehead S.E.X.y speaker. You wouldn't need two with the BetsyK's, but those Parts Express pre-built subs are cheap enough that you may as well!
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
Karl,
I modeled the TL's in Horn Response. I worked the original design out as a regular tapered TL, then I tried some models with various steps to see how that might affect it. It works very much as I expected, which is to say, great! The transient response sounds excellent to me. How the cabinet effects transients will depend on exactly what you are asking out. The TL's midbass lacks the "slam" I got from the BIB's, but I'm sure it will exceed a sealed box in that regard. It has been awhile since I tried a sealed box, but I suspect that the midrange on up isn't entirely different. If anything, I'm sure the TL is better as the speaker has more room to breath, and likely is being asked to work less hard.
If you are looking for "slam," that will always be a challenge with a little, low excursion woofer. I'd pick the biggest enclosure you can stand to give it as much help as possible. If you are looking for speed and microdynamics in the midrange and treble, I'd stick to 1.5 cu ft at a minimum. You don't want to have to stuff the enclosure too much and "choke" the dynamics. I haven't tried it myself, but if you go to a very small (1 cu ft or less) sealed box, you should be able to stuff it enough to get the bass in line (not too warm), but those micro-dynamics will the the first thing to suffer. The flip side is that the smaller sealed box will restrict excursion more, so the maximum dynamic range should be greater.
I attached an image from SketchUp. This is the TL with no sides, so you can see the internal folding and get the basic idea. The dimensions are a little off, and I can't figure out what I'm doing wrong. That is why I'm not showing all of them. If you needed this to go flat against a wall, you could face the terminus forward. As long as you've got an inch for them to breath, the rear vent is probably the way to go.
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
I modeled the TL's in Horn Response. I worked the original design out as a regular tapered TL, then I tried some models with various steps to see how that might affect it. It works very much as I expected, which is to say, great! The transient response sounds excellent to me. How the cabinet effects transients will depend on exactly what you are asking out. The TL's midbass lacks the "slam" I got from the BIB's, but I'm sure it will exceed a sealed box in that regard. It has been awhile since I tried a sealed box, but I suspect that the midrange on up isn't entirely different. If anything, I'm sure the TL is better as the speaker has more room to breath, and likely is being asked to work less hard.
If you are looking for "slam," that will always be a challenge with a little, low excursion woofer. I'd pick the biggest enclosure you can stand to give it as much help as possible. If you are looking for speed and microdynamics in the midrange and treble, I'd stick to 1.5 cu ft at a minimum. You don't want to have to stuff the enclosure too much and "choke" the dynamics. I haven't tried it myself, but if you go to a very small (1 cu ft or less) sealed box, you should be able to stuff it enough to get the bass in line (not too warm), but those micro-dynamics will the the first thing to suffer. The flip side is that the smaller sealed box will restrict excursion more, so the maximum dynamic range should be greater.
I attached an image from SketchUp. This is the TL with no sides, so you can see the internal folding and get the basic idea. The dimensions are a little off, and I can't figure out what I'm doing wrong. That is why I'm not showing all of them. If you needed this to go flat against a wall, you could face the terminus forward. As long as you've got an inch for them to breath, the rear vent is probably the way to go.
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
Attachments
Karl,
I'll try and get it to work. If all else fails, I draw in the dimensions and mail them to you. The design is really pretty simple, and also fairly flexible. If memory serves, I'm using a pound and a half of polyfill per enclosure. I stuffed only above the folds, denser towards the top, tapering off to the first bend.
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
I'll try and get it to work. If all else fails, I draw in the dimensions and mail them to you. The design is really pretty simple, and also fairly flexible. If memory serves, I'm using a pound and a half of polyfill per enclosure. I stuffed only above the folds, denser towards the top, tapering off to the first bend.
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
Hi Paul,
My Betsy K's are still in their boxes - I'd been thinking of trying 1cf sealed, but then realized just how big that is for a computer speaker and thought better of it. The mini-tl looks great for my alternate application though, and I'd be very interested in the plans for your cabinet as well.
My Betsy K's are still in their boxes - I'd been thinking of trying 1cf sealed, but then realized just how big that is for a computer speaker and thought better of it. The mini-tl looks great for my alternate application though, and I'd be very interested in the plans for your cabinet as well.
I have heard the Betsy in three different cabinet designs. An open baffle with bass support, a 1.3L sealed and a .5L sealed (but lossy) box. In sealed all by themselves they sound fine with detail galore. If you look carefully at the pictures you will notice i have a pair of beautiful wizzerless Betsy's. In the sealed box there are piezo's on the rear. On the open baffles are small compression drivers crossed around 11k.
Godzilla
Godzilla
Attachments
'Zilla,
What exactly was the "lossy" box? I've been thinking of trying to do something aperiodic for those that want small cabinets. I haven't found a good way to sim them, so it appears they depend entirely on trial and error. I'd be curious to hear any details you can provide.
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
What exactly was the "lossy" box? I've been thinking of trying to do something aperiodic for those that want small cabinets. I haven't found a good way to sim them, so it appears they depend entirely on trial and error. I'd be curious to hear any details you can provide.
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
>>> What exactly was the "lossy" box? I've been thinking of trying to do something aperiodic for those that want small cabinets.
The 'lossy' box is one that's not perfectly sealed. I have an old pair of nice wooden cabs with a hole for an 8" driver but the tweeter is missing two of its four screws so air escapes. I sim aperiodic boxes in WinISD by tuning to 20hz and making the vent .25" diameter... probably not the best way to sim LOL... and the results are usually the same or similar to a sealed cab. My quick sim of the Betsy this morning indicates a 1.5 cubic ft box sealed works pretty good as does a 2cf... -3 at around 65hz. Anything smaller seems to produce a big bass bump on paper. Listening to Betsy's in smaller sealed 'lossy' boxes sounds good to me in real world listening regardless of the simmed bump. Not sure the sim is indicative of what i hear. I would also like to try a simple 'picture frame' box for the Betsy... a shallow box maybe 16"w x 20"h x 2"d without any back at all and see what i get. My sim shows a smooth gradual slope from 300hz to 150hz... so a simple sub rolled in should provide satisfying bass while the Betsy does the rest. I will post pics of the sims when i can. Certainly not the optimal setup for the Betsy but a real world project that should provide 'good enough' performance while letting the driver do it's thing. I bet the imaging will be to die for (for the small OB anyway) that measurements don't reveal and the sound will be dynamic and detailed.
Godzilla
The 'lossy' box is one that's not perfectly sealed. I have an old pair of nice wooden cabs with a hole for an 8" driver but the tweeter is missing two of its four screws so air escapes. I sim aperiodic boxes in WinISD by tuning to 20hz and making the vent .25" diameter... probably not the best way to sim LOL... and the results are usually the same or similar to a sealed cab. My quick sim of the Betsy this morning indicates a 1.5 cubic ft box sealed works pretty good as does a 2cf... -3 at around 65hz. Anything smaller seems to produce a big bass bump on paper. Listening to Betsy's in smaller sealed 'lossy' boxes sounds good to me in real world listening regardless of the simmed bump. Not sure the sim is indicative of what i hear. I would also like to try a simple 'picture frame' box for the Betsy... a shallow box maybe 16"w x 20"h x 2"d without any back at all and see what i get. My sim shows a smooth gradual slope from 300hz to 150hz... so a simple sub rolled in should provide satisfying bass while the Betsy does the rest. I will post pics of the sims when i can. Certainly not the optimal setup for the Betsy but a real world project that should provide 'good enough' performance while letting the driver do it's thing. I bet the imaging will be to die for (for the small OB anyway) that measurements don't reveal and the sound will be dynamic and detailed.
Godzilla
Attached are charts for sealed, vented and small open baffle speaker for Betsy. I left some other drivers in the open baffle sim for comparison. These boxes work well enough. If you like the Betsy's dynamic, detailed sound and don't mind a sub i think the small open baffle might be an interesting idea as a substitute for a bookshelf sized speaker. I should sim the Betsy on a larger open baffle too...
Godzilla
Godzilla
Attachments
Just so folks don't get confused: the BetsyK is the ideal choice for nearly all boxes. Though the Betsy can be made to work, the higher Q alignments that usually result won't be for everybody.
'Zilla, I've wondered about the Betsy in something akin to a small open backed cabinet (maybe even down around a half cubic foot), like some vintage stuff. I don't know which would give better bass, the BetsyK in a real aperiodic box or the Betsy in something really lossy, where the back is full of holes.
It is also worth noting that if you are considering a sub with the small cabinet, it may be worth while to use a higher Qts alignment (like your Betsy in a sealed box) in conjunction with a high pass filter (especially line level, but big motor run caps could work too). That would bring the response down and further reduce excursion. Just a thought.
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
'Zilla, I've wondered about the Betsy in something akin to a small open backed cabinet (maybe even down around a half cubic foot), like some vintage stuff. I don't know which would give better bass, the BetsyK in a real aperiodic box or the Betsy in something really lossy, where the back is full of holes.
It is also worth noting that if you are considering a sub with the small cabinet, it may be worth while to use a higher Qts alignment (like your Betsy in a sealed box) in conjunction with a high pass filter (especially line level, but big motor run caps could work too). That would bring the response down and further reduce excursion. Just a thought.
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
>>> I don't know which would give better bass, the BetsyK in a real aperiodic box or the Betsy in something really lossy, where the back is full of holes.
I wonder too which would be better?
>>> It is also worth noting that if you are considering a sub with the small cabinet, it may be worth while to use a higher Qts alignment (like your Betsy in a sealed box) in conjunction with a high pass filter (especially line level, but big motor run caps could work too). That would bring the response down and further reduce excursion. Just a thought.
That's a good thought! I've only simmed the driver i have with the higher qts... the BetsyK may be better in the sealed or aperiodic boxes for sure. It may be fun to compare Betsy on a small OB to BetsyK in small sealed/aperiodic. I would imagine more base from the BetsyK but the imaging could distinguish itself on the open baffle providing a different advantage (or flavor) over the other. An open back box like the old vintage boxes is probably what i will build for my Betsy in the near future.
Neat stuff to think about.
Godzilla
I wonder too which would be better?
>>> It is also worth noting that if you are considering a sub with the small cabinet, it may be worth while to use a higher Qts alignment (like your Betsy in a sealed box) in conjunction with a high pass filter (especially line level, but big motor run caps could work too). That would bring the response down and further reduce excursion. Just a thought.
That's a good thought! I've only simmed the driver i have with the higher qts... the BetsyK may be better in the sealed or aperiodic boxes for sure. It may be fun to compare Betsy on a small OB to BetsyK in small sealed/aperiodic. I would imagine more base from the BetsyK but the imaging could distinguish itself on the open baffle providing a different advantage (or flavor) over the other. An open back box like the old vintage boxes is probably what i will build for my Betsy in the near future.
Neat stuff to think about.
Godzilla
BetsyK sim I did sometime ago for 3rd order sealed box shows ~350uF "should" flatten the passband and lower F3 but a series capacitor of this value will raise the output and in-band excursion. A leaky box may be good - do nearfield mic and muck with holes/whatever while watching on RTA
An externally hosted image should be here but it was not working when we last tested it.
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Freddi or anyone...
Can anyone explain or does anyone know, all things being equal, would a driver have greater power handling in a sealed or aperiodic box? I am wondering how allowing the box to breath might change how the speaker lives in that box... is it happier in one box or the other?
I feel like building the Betsy in a small OB just for kicks... will hide a small sub under my office scanner and keep it a secret. Shhhh!
TIA
Godzilla
Can anyone explain or does anyone know, all things being equal, would a driver have greater power handling in a sealed or aperiodic box? I am wondering how allowing the box to breath might change how the speaker lives in that box... is it happier in one box or the other?
I feel like building the Betsy in a small OB just for kicks... will hide a small sub under my office scanner and keep it a secret. Shhhh!
TIA
Godzilla
I'd think it'd burn up at the same rate 
- a leaky box if used with lps and phono preamp without warp filter ought to be worse.
I'd like to see a discussion of distributive leaky vents - and have seen the cases with small holes or slits produce high air velocity and introduce harmonic distortion below the passband when driven with sine-wave - but does music approach sine-condition?
- a leaky box if used with lps and phono preamp without warp filter ought to be worse.I'd like to see a discussion of distributive leaky vents - and have seen the cases with small holes or slits produce high air velocity and introduce harmonic distortion below the passband when driven with sine-wave - but does music approach sine-condition?
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Generally, power handling in it's strictest sense shouldn't be an issue with fullrangers. With most higher efficiency fullrangers, you will exceed Xmax at power levels well below the voice coil's thermal limit. Where excursion isn't controlled by any acoustic means, like an OB, it won't take more than a couple of watts to exceed where the speaker sounds good. And, it will only take a couple more to get the voice coil out of the gap. I can imagine that some BLH's may control excursion enough to allow you to through some serious watts at the speaker, but that isn't what we're talking about here. Even if thermal issues somehow enter consideration, there shouldn't be enough air moving in and out of the aperiodic box to make a difference. Stuffing in the sealed box would limit the speakers ability to shed heat. But, I really don't think that is the primary concern in the vast majority of home fullranger applications. IMO, if you need more than a couple of watts, a single driver isn't for you. Sure, there are drivers with higher excursion, but that doesn't mean using it is a good idea from a distortion standpoint. Thermal concerns are important in pro audio, but that is an entirely different ball game.
What you want is to limit excursion to keep distortion down. Both the sealed and aperiodic boxes should do a decent job of that. With a woofer assisted OB, you'll get better results with some sort of high pass filter. However, in the extreme near field (are you thinking on a desk?), it may not be worth the hassle.
If you are looking for small OB inspiration, how about heavy duty (1/4" wall) aluminum stock pots? They cost a bit of $$ in big sizes (like 40 quarts), but I'd love to put a pair of Betsys in the bottom of some shiny cylinders. Maybe even big roasters on a desk.
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
What you want is to limit excursion to keep distortion down. Both the sealed and aperiodic boxes should do a decent job of that. With a woofer assisted OB, you'll get better results with some sort of high pass filter. However, in the extreme near field (are you thinking on a desk?), it may not be worth the hassle.
If you are looking for small OB inspiration, how about heavy duty (1/4" wall) aluminum stock pots? They cost a bit of $$ in big sizes (like 40 quarts), but I'd love to put a pair of Betsys in the bottom of some shiny cylinders. Maybe even big roasters on a desk.
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
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